Investigation of Energy Transfer Processes in Downconversion Luminescence in BaY2F8 Crystals with Coactivation by Tb3+–Yb3+ Ions

The spectral and kinetic characteristics of BaY2F8 crystals with coactivation by Tb–Yb ions under excitation at a wavelength of 266 nm were studied. Luminescence of Yb3+ ions was detected in the NIR spectral range because of charge transfer processes. Studies at low-temperature have not shown the cooperative energy transfer, as well as single-photon processes of direct energy transfer to acceptor ions have been found. The quantum yields were measured, taking values of 70.3, 49.3, and 55.05% for 2, 5, and 10 at % ytterbium ion concentrations, respectively.